GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"- GRB 090518: Enhanced Swift-XRT position
- GRB 090518: Swift detection of a burst
- GRB 090515: Swift/BAT spectral lag results
- GRB 090516: Swift-BAT refined analysis
- GRB 090516: VLT spectrum (correction & update)
- GRB 090516: GROND OBSERVATIONS
- GRB 090516: VLT redshift
- GRB 090516 - Zadko Telescope observations
- GRB 090516: NOT optical observations
- GRB 090516: Swift XRT refined analysis
- GRB 090516: Swift/UVOT Observations
- GRB 090516: Enhanced Swift-XRT position
- GRB 090516: Faulkes Telescope South optical afterglow
- GRB 090516: Swift detection of a burst
- GRB 090515: VLA observations
- GRB 090515: Lick Upper Limits
- GRB 090515: ROVOR Upper Limit
- GRB 090515: MMT/MMIRS NIR Upper Limit
- GRB 090515: Swift/UVOT Observations
- GRB 090515: Swift-XRT refined analysis
- GRB 090515: Enhanced Swift-XRT position
- GRB 090509: Fermi GBM observation
- GRB 090515: Swift-BAT refined spectral analysis
- GRB 090515: Swift-BAT refined analysis
- GRB 090509 - Zadko Telescope observations
- GRB 090515: Gemini-N upper limit
- GRB 090515: WIYN NIR Upper Limit
- GRB 090515: Super-LOTIS Upper Limits
- GRB 090515: PAIRITEL Upper Limits
- GRB 090515: KAIT optical upper limits
- GRB 090515: ROTSE-III Optical Limits
- GRB 090515: Swift detection of a short burst
- GRB 090510: Suzaku WAM observation of the prompt emission
- GRB 090510, Radio limits
- GRB090510: VLT/FORS2 spectroscopic redshift
- GRB 090510: GROND observations
- GRB 090510: Swift/UVOT host galaxy candidates
- GRB 090510: Fermi-LAT follow-up analysis
- GRB 090509, further Swift-BAT refined analysis
- Fermi Gamma-ray Burst Monitor trigger 263649437 is not a GRB
- GRB 090510B: Fermi GBM detection
- GRB 090502: Fermi GBM detection
- GRB 090510: correction to GCN 9344
- Konus-Wind observation of GRB 090510
- AGILE detection of GRB 090510
- GRB 090510: UVOT refined analysis
- GRB 090510: Swift XRT refined analysis
- GRB 090510: correction to coordinates in GCN 9338
- GRB 090510: Enhanced Swift-XRT position
- GRB 090510: NOT afterglow confirmation
- GRB 090510: Swift-BAT refined analysis
- GRB 090510: Fermi GBM detection
- GRB 090509: Swift-BAT refined analysis
- Fermi LAT detection of GRB 090510
- GRB 090509, SMARTS optical/IR afterglow observations
- GRB 090510: Swift/UVOT Detection of a Candidate Optical Afterglow
- GRB 090510: Swift detection of a short hard burst
- GRB 090408: optical upper limit
- GRB 090418A: optical observation
- GRB 090509: GROND further analysis and redshift limit
- GRB 090509: REM NIR afterglow
- GRB 090509: GROND afterglow candidate
- GRB 090509: Swift detection of a burst
- GRB 090323: optical observations
- GRB 090423: optical limit
- GRB 090423: 250 GHz upper limit for a z=8.2 GRB with MAMBO-2 at the IRAM 30m
- GRB 080913: 250 GHz upper limit for a z=6.7 GRB with MAMBO-2 at the IRAM 30m
- GRB 090424: optical observations
- GRB 090427: GROND observations
- GRB 090429A: ROVOR magnitude limit
- ICSP VLF observation of GRB090427 from two receivers
- ICSP VLF observation of GRB090424 from four receivers
- Refined analysis of ICSP VLF observation of SGR J1550-5418 bursts on 22nd January, 2009
- GRB 090428B: Suzaku WAM observation of the prompt emission
- GRB 090424, SMARTS optical/IR afterglow monitoring
- GRB 090426: optical observations
- GRB 090429D: Fermi GBM detection
- GRB 090429C: Fermi GBM detection
- GRB 090429B: Swift/UVOT Upper Limits
- GRB 090429A: Swift/UVOT Upper Limits
- GRB 090427: pseudo-z= 1.48 from prompt emission spectrum
- GRB 090429B: Gemini-N further nIR observations
- GRB 090424: YNAO-GMG observations
- GRB 090429A: Swift-XRT refined analysis
- GRB 090429A: GROND upper limits
- GRB 090427C: Fermi GBM detection
- GRB 090427B: Fermi GBM detection
- GRB 090426C: Fermi GBM detection
- GRB 090426B: Fermi GBM detection/observation
- GRB 090429B: Swift XRT refined analysis
- GRB 090429A: Enhanced Swift-XRT position
- Konus-Wind observation of very bright GRB 090427
- GRB 090428B: Fermi GBM detection
- GRB 090428: Fermi GBM detection
- GRB 090418A BVRcIc field calibration
- GRB 090426: GAO 150cm telescope Optical Observation
- GRB 090429B: RIMOTS optical upper limits
- GRB 090429B: Swift-BAT refined analysis
- GRB 090429A: Swift-BAT refined analysis
- GRB 090429B: Enhanced Swift-XRT position